Planning to Implement Your Watershed Management Program: The USGR Feasibility Study
A Feasibility Study was performed to evaluate seven proposed regional projects identified in the Upper San Gabriel River Watershed Management Area (USGSR WMA) Enhanced Watershed Management Program (EWMP). The study addressed project suitability with respect to each site’s implementation and operations. The implementation components include expected design flows, water quality, potential for infiltration, identification of major components and equipment, and basic site plans. The study also included estimates for operations and maintenance needs and costs, as well as monitoring plans, for each of the proposed sites.
Through a collaborative effort with the USGR WMA Cities, Tetra Tech developed site-specific project concepts that balanced diversion rates, available project areas, groundwater considerations, and costs to provide solutions that allow the Cities to achieve their shared pollutant load reduction targets. The project team made multiple updates to the EPA SUSTAIN model to allow for site- and BMP-specific performance data and refined costing information to be incorporated and reflect the most realistic full project costs to be weighed in BMP configuration optimization. This approach more accurately predicts the realized performance and pollutant load reductions for the overall watershed allowing the Cities to strategically invest where impact is highest. Implementing this approach, as well as considering multiple site-specific constraints including infiltration, indicated that compliance targets could be met with half of the proposed BMP area resulting in a significant cost savings.
Through the course of the Feasibility Study, the optimal project designs for the regional structural projects, their associated performance, and costs are detailed. The combined performance of the final proposed regional structural BMP configurations is predicted to meet and exceed the WMP’s pollutant reduction compliance targets, while minimizing footprint sizes and, therefore, substantially reducing the estimated costs for compliance.
Participants of this session will have an understanding of how to transition from the development of a watershed management plan and the key steps for the development of a technologically advanced stormwater BMP project. The session will include an interactive discussion about project prioritization, BMP project benefits, and the value of advanced stormwater capture strategies. The session is aligned with the conference theme “Connecting the Drops from Summit to Sea” by addressing opportunities for urban stormwater practitioners to hone in on efficient and sustainable methods for achieving regional pollutant management in accordance with the NPDES permits and TMDLs associated with each watershed.